[PATCH 27/27] perf record: Store PERF_RECORD_FINISHED_ROUND only for nonempty rounds

From: Arnaldo Carvalho de Melo
Date: Fri Jul 25 2014 - 11:39:27 EST

From: Jiri Olsa <jolsa@xxxxxxxxxx>

Currently we store PERF_RECORD_FINISHED_ROUND event each time
we go throught mmap buffers no matter if it contains any data,
which is useless.

Forcing the PERF_RECORD_FINISHED_ROUND event to be stored any
time we finished the round AND wrote at least one event.

Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Acked-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Acked-by: David Ahern <dsahern@xxxxxxxxx>
Cc: Corey Ashford <cjashfor@xxxxxxxxxxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jean Pihet <jean.pihet@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1406300177-31805-19-git-send-email-jolsa@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
tools/perf/builtin-record.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 4a1a54265b04..4869050e7194 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -238,6 +238,7 @@ static struct perf_event_header finished_round_event = {

static int record__mmap_read_all(struct record *rec)
+ u64 bytes_written = rec->bytes_written;
int i;
int rc = 0;

@@ -250,7 +251,12 @@ static int record__mmap_read_all(struct record *rec)

- rc = record__write(rec, &finished_round_event, sizeof(finished_round_event));
+ /*
+ * Mark the round finished in case we wrote
+ * at least one event.
+ */
+ if (bytes_written != rec->bytes_written)
+ rc = record__write(rec, &finished_round_event, sizeof(finished_round_event));

return rc;

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